Turbogenerator



G. J. LEHMANN TURBO-GENERATOR Nov. 2, 1948.

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IN VEN TOR. GEF/4R0 I il/M4N G. J. LEHMANN TURBO-GENERATOR Nov. 2, 1948.

2 Sheets-Sheet 2 Filed June '7, 1944 IN V EN TOR. @EFH/70 JI fl/MANN A TWIPIVL'Y Patented Nov. 2, 1948 TURBOGENERATOR Gerard J. Lehmann, New York, N. Y., assignor to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application June 7, 1944, Serial No. 539,228

14 Claims.

The present invention relates to low-power electrical generating systems, and more particularly to turbo generators of low power.

One object of my invention is to provide a compact, self-contained electrical generating system having low fuel consumption and giving long periods of service without maintenance.

A further object of my invention is to provide a small, low-power mercury vapor turbine operating at low vapor pressure and good efficiencies.

A still further object of my invention is to provide a turbo generator sealedv as a unit within a completely closed housing of relatively small size.

An additional object of my invention is to provide a mercury vapor turbo generator in which no vapor seal between the turbine and generator is necessary. i

It is highly desirable to feed small turbines with a low-pressure fluid. This is due to the fact that the influence of the ambient vapor on the friction losses of the wheel in a low-power turbine is great. These losses, caused by the viscosity of the vapor, are greatly reduced if the turbine rotates in a lowpressure atmosphere. Furthermore, the use of conventional pressures gives to the'area of any section crossed by the vapor a value so small that mechanical construction is impracticable. By reducing the pressure, the specific volume of the vapor increases, and the dimensions of all elements (nozzles and blades) become large enough to be mechanically feasible.

The available energy in one gram of mercury vapor is about one-ninth the available energy in one gram of water vapor. When this available energy is transformed into kinetic energy in a nozzle, the result is a velocity for the mercury vapor of about one-third that of steam. Thus the use of mercury makes simultaneously possible the low pressures needed by the mechanical struc-1 ture and the high temperatures needed for thermodynamic efficiency. With water it is impossible to have simultaneously a low pressure, a low speed of the expanded vapor, and a high thermodynamic efficiency.

The complete system of the present invention utilizes the following umts:

l. A boiler, a burner, and a fuel tank.

2. The turbo-generator.

3. A condenser.

The burner is utilized to heat the liquid mercury coming from the condenser, to vaporize the liquid, and to superheat the vapor. After total expansion in a single nozzle, the mercury vapor jet rotates a double impulse wheel the blades of which have a linear velocity in a predetermined ratio to the vapor velocity. The turbine wheel and the alternator rotor are mounted on the same shaft. The vapor thereafter goes to the condenser and is cooled by a free circulation of air. The condensed mercury due to its very high density returns to the boiler by gravity, thus eliminating any feeding pump.

Since the turbine is rotated by an entirely expanded vapor, it operates at a temperature low enough so that the bearings and the alternator can be enclosed within the turbine body itself. Therefore, no mercury vapor seal is required along the rotating shaft. Also, since the mercury and its vapor flow in a closed cycle inside a sealed system, the end result is a stability of operation over a considerable period of time without maintenance.

The above features make the present invention particularly suited for use in cases where relatively low power is needed for the supply of radio equipment, such, for example, as in repeater stations located in areas where infrequent servicing is desired. However, the disclosed system may obviously be utilized in many other instances where electrical energy is required.

Other objects and advantages of the invention will be apparent from the following description of preferred forms of the invention and from the drawings, in which:

Fig. 1 is a schematic view partly in section of a preferred form of electric generating system in accordance with the present invention;

Fig. 2 is a sectional view of the turbo-generator utilized in the system of Fig. 1; and

Figs. 3 and 4 are sectional views of modifications of the turbo-generator of Fig. 2.

In the electrical generating system of Fig. 1 is shown a boiler I positioned on a base 2. Within boiler I is a heating coil 3 encircling a burner 4. A tank 5 supplies fuel to burner 4 through a pipe 6. Tank 5 is positioned on base 2 by means of a support l.

Extending vertically above boiler I is a flue 8. A hollow member 9 positioned on base 2 encloses fuel tank 5 and its support 'I. Carried by member 9 is a condenser I0, while a second fiue II eX- tends upwardly from the condenser. The upper portions of fiues 8 and I I are curved toward each other and intersect at I2 so as to provide a common outlet I3.

Secured to a horizontal extension I4 of condenser I0 is a mercury-vapor turbo-generator I5. A conduit I6 partly enclosed within flue 8 returns the liquid mercury by gravity feed from condenser I 3 III to the lower portion of heating coil 3. A second conduit Il, also partly enclosed within ue 8, carries the mercury vapor from the upper end of heating coil 3 to the turbo-generator I 5. Cooling air for the condenser I is provided by an intake I8 associated with the condenser and supported by hollow member A9. Since the condenser I 0 may be of any suitable type known in the art, the details thereof are not shown.

Burner 4 is provided with fuel from tank 5 through pipe 6. Liquid mercuy from condenser III flows through conduit I6 and is conducted by gravity to the lower end of coil 3. After being heated and vaporized in the coil, the mercury vapor is carried by conduit I1 to the turbo-generator I5.

Following its expansion in the turbine, the exhaust mercury vapor is liquified in condenser I0 by the action of fresh cooling air entering intake I8 and being drawn up the flue II by heat liberated from the mercury vapor. A draft is also caused in ue 8 by the heated air and smoke resulting from the action of burner 4. The heated air in both flues 8 and II escapes through outlet,

I3, at least the upper portion of ue 8 being of smaller diameter than ue I I to provide an annular opening between members 8 and II. It should be noted that a draft is established in ue 8 as soon as burner 4 is in operation. Due to their common outlet I3, a draft is consequently established at the same time in flue II even though no heat is being liberated in condenser I0. Thus a cooling flow of fresh air through the condenser is provided immediately upon operation of burner 4.

Fig. 2 shows the constructional details of the turbo-generator I5. One preferable design of the assembly would be on a scale approximately twice that shown in the drawings. The mercury vapor conducted by conduit I'I from coil 3 enters the turbine, nozzle I9 through throat 20. Past the throat, the surface of the nozzle I9 increases and changes from a circular to an annular substantially conic section. Adjacent the aperture of the nozzle is mounted the first of two sets of stationary blades 2 I 2 IA which defiects the mercury vapor jet and directs the vapor onto the rst of two sets of rotating blades 22, 22A. Thus there is produced an annular series of jets of vapor from a single throat, this vapor ring being directed Aat any instant against each of the first set of rotating blades 22. After passing blades 22 the vapor is directed by the second set of stationary blades 2IA to the second set of rotating blades 22A. Since the mercury vapor reaches substantially its full expansion upon passing from nozzle I9, the second set of blades have substantially the same area as the first set.

Both sets of blades 22, 22A are carried by a wheel 23 which is securely mounted on a shaft 24. A pair of bearings 25 position shaft 24 within the turbine body. An outlet 26 passes the expanded mercury vapor from the turbine chamber to extension I4 of condenser I0.

The turbo-generator assembly I5 is provided with a chamber containing an alternator 28. This alternator comprises a. stator winding 29 and a permanent magnet rotor 30 mounted on shaft 24. For optimum operation a three phase winding is preferable. The magnetic field in the rotor is constant, which eliminates all losses due to flux variation in the rotating magnet. In order to overcome any insulation diflicu'lty resulting from the low pressure mercury vapor atmosphere, the volti esteis Dr Openings 3| between the turbine chamber and the alternator chamber 21 permit free access of the mercury vapor to the portion of the chamber housing the alternator mechanism. Due to this method of construction, no packing members or other seals are required along shaft 24 between the turbine and generator. A glass seal 32 is provided at each point where the alternator electrical connections enter the turbine body.

For convenience of assembly the turbine body is preferably made in three sections 33, 34 and 35. these sections being secured together at 35 and 31 by any desired means that, with glass seals 32, will result in a gas-tight assembly. This securing means for example may comprise welding of the sections. Similar securing means such as welding is employed to produce gas-tight connections between the turbine body on one hand and conduit II and extension I4 of condensery I0 on the other.

In a preferred form.of electrical generating system constructed in accordance with the present invention, in which the electrical power given by the alternator is watts, the working temperatures may range from 357 C. for the saturated vapor to C. for the expanded vapor. This results in the boiler being at nearly atmospheric pressure while the pressure in the condenser is equivalent to approximately .8 millimeter of mercury. The thermo-dynamic emciency of the system under these conditions is close to 36.4%. However, it should be clearly understood that the above figures are given solely by way of example, and that any or all of such figures may be modified to meet particular conditions.

It will be noted that in the preferred example given the temperature of the expanded vapor is 120 C. This is sufficiently low to permit the vapor to dissipate a percentage of the heat 'generated in the bearings 25 and in the winding 29 of alternator 28.

In Fig. 3 is shown a modified form of turbogenerator operating on the same principle as that shown in Fig. 2. The two sets of rotating blades 22a are carried by separate rotor wheels 23a on opposite ends of shaft 24a. The alternator assembly is positioned between the turbine wheels so that the rotating magnet 30a is balanced between the power-receiving extremities of shaft 24a. In this type of construction the inlet and outlet for the mercury vapor are positioned in linear relation to one another. i

In Fig. 4 is shown another modification of the turbo-generator of Fig. 2 in which the mercury vapor `iet is applied longitudinally of shaft 24h as in Fig. 3 instead of radially as in Fig. 2. In contrast to the form shown in Fig. 3, however, both sets of rotating blades 22h aremounted on a single rotor wheel 23h on one end of shaft 24b. The inlet and outlet for the mercury vapor are substantially at right angles to one another in the manner of Fig. 2, rather than in the linear relation existing in Fig. 3.

Many other structural modifications of a turbogenerator in accordance with my invention will readily ,occur to those skilled in the art. While I have described above the principles of my invention in connection with specific apparatus, and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of my invention as set forth in the objects of my invention and the accompanying claims.

claim:

1. A mercury-vapor turbo-generator comprislng a mercury-vapor turbine, a. generator operated by said turbine, a gas-tight housing enclos-3 ing both said turbine and said generator, and gas tight supply means for supplying said mercury vapor to said turbine means for permitting passage of said mercury vapor between said turbine and said generator.

2. A mercury-vapor turbo-generator comprising a mercury-vapor turbine, a generator operated by said turbine, a source of mercury vapor means for cooling said vapor, a gas-tight housing enclosing both said turbine and said generator, and conduit means secured between said housing, said source and said cooling means in gas-tight relation to conduct mercury vapor from said source to and from said turbine back to said cooling means in a closed cycle.

3. A turbo-generator according to claim 2, further comprising means associated with said conduit means for heating said mercury vapor and a condenser for cooling said vapor, said heating means and said condenser being -provided with separate nues having a common outlet.

4. In a compact turbo-generator assembly of the mercury-vapor type, the combination of a substantially gas-tight body, partitioning means forming separate compartments within said body for the generator and the turbine portions of said assembly, and a power shaft within the generator compartment and extending through said partitioning means into the turbine compartment of said assembly, said partitioning means having an opening therein for permitting free passage of mercury vapor between the turbine portion of said assembly and said generator compartment.

5. A turbo-generator assembly according to claim 4, further comprising a. turbingwheel carried by said power shaft within the turbine portion of said assembly, a plurality of blades around the periphery of said Wheel, and a substantially annular stationary nozzle having a single throat and a plurality of deflecting means, whereby the mercury vapor passing through said throat will be shaped by said nozzle into an annular series of jets directed against the blades of said wheel.

6. In a compact turbo-generator of the mercury-vapor type, the combination of a body formed in a plurality of sections, one of said body sections being formed with a circular throat, a nozzle for shaping 'the mercury vapor passing through said circular throat into a substantially annular series of jets of vapor, a second of said body sections designed to form with said i'lrst body section e. turbine compartment, a rotatable power shaft passing through and supported in part by said second body section, a turbine wheel on said shaft within said turbine compartment, a plurality of blades around the periphery of said wheel and in the path of said annular series of jets of vapor, a third body section designed to form with said second body section a generator compartment, said power shaft extending into said generator compartment and being in part supported by said third body section, and a generator rotor on said shaft within said generator compartment.

7. A turbo-generator according to claim 6, in which said second body section is formed with a plurality of openings therein so as to permit free passage of mercury vapor between said turbine compartment and said generator compartment.

8. A turbo-generator according to claim 6, further comprising gas-tight connections between said three body sections.

9. A turbo-generator according to claim 6, further comprising a stator coll within said generator compartment and encircling said rotor, said rotor comprising a permanent magnet, one or more electrical connections to said coil passing through said body, and means for rendering gastight the points at which said electrical connections pass through said body.

10. In a. low-power generating system, a mercury-vapor turbo-generator, a source of liquid mercury, heating means to vaporize said liquid mercury, means for conducting the vaporized mercury to said turbo-generator, a condenser receiving the vapor output from said turbo-generator, a flue for said heating means, and a. flue for the heat liberated in said condenser, both said flues having a common outlet so that the heated air rising in said first-mentioned flue will create a draft in said last-mentioned flue regardless of whether heat is being liberated in said condenser.

11. In a low-power generating system, a source of fuel, a burner receiving fuel from said source, a flue for said burner, a mercury-vapor turbogenerator, a source of liquid mercury, means receiving heat from said burner to vaporize said liquid mercury, means for conducting the vaporized mercury to said turbo-generator, a con-- denser receiving the vapor output from said turbo-generator, means returning the liquid mercury from said condenser to said heat receiving means, and a nue for the heat liberated in said condenser, both said iiues having a common outlet so that heated air rising in said rst-mentioned fiue as a result of the operation of said burner will create a draft in said last-mentioned ue regardless of whether heat is being liberated in said condenser.

12. A low-power generating system according to claim 11 in which the means returning the liquid mercury from said condenser to said heat receiving means comprises a gravity feed.

13. A low-power generating system according to claim 11 in which said flues are vertically positioned side-by-side, and in which the mount of said turbo-generator extends horizontally between said first-mentioned ilue and said condenser.

14. A low-power generating system according to claim 11, further comprising a base for said burner, and a hollow condenser support on said base, said source of fuel being enclosed Within said support.

GERARD J. LEHMANN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 104,726 Fuller June 28, 1870 289,560 Richardson Dec. 4, 1883 298,230 Peer May 6, 1884 305,575 Culver Sept. 23, 1884 424,918 Brown Apr. l, 1890 469,589 Pack Feb. 3, 1892 525,390 McElroy Sept. 4, 1894 548,930 Sargent Oct. 29, 1895 613,694 Lundell Nov. 8, 1898 768,593 Emmet et al Aug. 30, 1904 796,721 Heilmann Aug. 8, 1905 (Other references on following page) Number Number Name Date Selppel Mar. 12, 1940 Seippel Nov. 25, 1941 Yost May 2, 1944 FOREIGN PATENTS Country Date lGreat Britain May 28, 1926 Germany July 20, 1922 

